Polarized fluorescence microspectroscopy was applied to characterize conformations of two alkyl chain-labeled NBD phospholipids in three model membranes. Our approach revealed two coexisting probe conformations with different fluorophore dipole orientations relative to the membrane. The relative populations of conformations, estimated by a numerical model, indicated a specific sensitivity of the two probes to molecular packing with cholesterol. The method can be directly applied to study lipid rafts and nanodomains or membrane protein conformations.
COBISS.SI-ID: 26970919
In the paper a micro-scale mathematical model of blood clot dissolution based on coarse-grained molecular dynamics is presented. In the model, blood clot is assumed as an assembly of blood cells interconnected with elastic fibrin bonds, which are cleaved either biochemically (bond degradation) or mechanically (bond overstretching) during flow-mediated thrombolysis. The results of simulations indicate that a blood clot dissolution process progresses by a blood flow promoted removal of clot fragments of which sizes are flow-dependent. These findings are in a good agreement with the results of our recent optical microscopy experimental studies on dissolution model blood clots as well as with clinical observations. The results of the study are relevant for better understanding of risk factors for further embolization of the removed thrombotic material in microvasculature.
COBISS.SI-ID: 26585383
Pulsed gradient spin echo is an established NMR method of measuring molecular translation. Its dynamic range is limited by relaxation and hardware. We were able to extend the limit by modifyning the method and instead of changing the diffusion time, employed the variation of encoding time. This makes the method sensitive to molecular dynamics at higher frequencies, high enough to detect important polymer dynamics change from Rouse to reptation mode. No other method is able to tast in that region and the results are very important in development of molecular dynamics model. The results confirm a model of constraint release in a system of entangled polymer chains as a sort of tube Rouse motion.
COBISS.SI-ID: 27404327
We systematically analyzed our spectral fitting models and bleaching correction algorithms for fluorescence microspectroscopy. The introduced approaches enable the use of photosensitive probes with weaker spectral response to environmental changes, which will extensively broaden the experimental scope of the method. The value of nanometre peak position resolution and position-dependent bleaching rate imaging were demonstrated by observation of individual vesicles in different lipid phases and phase transitions between them.
COBISS.SI-ID: 27156007
A small series o fluorophores was synthesized by linking of 7-(diethylamino)coumarin and different aromatic systems with oxazole. Synthesized dyes display red shift of absorption as well as emission spectra. Fluorescence emission spectra in solvents of increasing polarity exhibit decrease of fluorescence intensity and red shift of emission maxima. Under our experimental conditions synthesized fluorophores display excellent photostability compared to NBD type probes. 7-(diethylamino)coumarin represented also the basis of for a small series of double spin-fluorescent probes. The influence of distance between fluorophore and nitroxide was examined with these probes. Several pH dependant probes of rhodamine type were also evaluated in regard to their photophysical properties.
COBISS.SI-ID: 3497585